Semiclassical gravitational effects near a singular magnetic flux

We consider the backreaction of the vacuum polarization effect for a massive charged scalar field in the presence of a singular magnetic massless string on the background metric. Using semiclassical approach, we find the first-order (in $\hbar$ units) metric modifications and the corresponding gravitational potential and deficit angle. It is shown that, in certain region of values of coupling constant and magnetic flux, the gravitational potential and deficit angle can be positive as well as negative over all distances from the string and can even change its sign. Unlike the case of massless scalar field, the gravitational corrections were found to have short-range behavior.Comment: 14 pages, 4 figures, journal versio

Induced vacuum energy-momentum tensor in the background of a d-2 - brane in d+1 - dimensional space-time

Charged scalar field is quantized in the background of a static d-2 - brane which is a core of the magnetic flux lines in flat d+1 - dimensional space-time. We find that vector potential of the magnetic core induces the energy-momentum tensor in the vacuum. The tensor components are periodic functions of the brane flux and holomorphic functions of space dimension. The dependence on the distance from the brane and on the coupling to the space-time curvature scalar is comprehensively analysed.Comment: 32 pages, 3 figures, journal version, some references adde

Fractional electric charge of a magnetic vortex at nonzero temperature

An ideal gas of twodimensional Dirac fermions in the background of a pointlike magnetic vortex with arbitrary flux is considered. We find that this system acquires fractional electric charge at finite temperatures and determine the functional dependence of the thermal average and quadratic fluctuation of the charge on the temperature, the vortex flux, and the continuous parameter of the boundary condition at the location of the vortex.Comment: 25 pages, 5 figures, journal version, minor changes, Eqs.(3.2)-(3.5) correcte

Some constraints on the Yukawa parameters in the neutrino modification of the Standard Model (nuMSM) and CP-violation

The equations connecting elements of the Yukawa matrix to elements of the active neutrino mass matrix in the \nu MSM theory (an extension of the Standard Model by a singlet of three right-handed neutrinos) was analyzed, and explicit relations for the ratio of the Yukawa matrix elements through elements of the active neutrino mass matrix were obtained. This relation can be used for getting more accurate constraints on the model parameters. Particularly, with the help of the obtained results we investigated CP-violating phase in the \nu MSM theory. We demonstrate that even in the case when elements of the active neutrino mass matrix are real the baryon asymmetry can be generated also.Comment: 14 pages, 2 figures, many clarifications and references adde